[autotest] Skip update_machine_information if job.machine is empty

For a suite job, which is hostless, tko parser still tries to update machine
info where machine name is empty(''). This should be skipped to avoid
unnecessary db write. When multiple suites finished around the same time,
they all try to update that tko_machines record, which may lead to timeout on
lock wait.

TEST=local run suite

Change-Id: I0c97ff0d401a0e24b6d712d7bdb4f4c2ba4bbfbc
Reviewed-on: https://chromium-review.googlesource.com/305503
Commit-Ready: Dan Shi <dshi@chromium.org>
Tested-by: Dan Shi <dshi@chromium.org>
Reviewed-by: Fang Deng <fdeng@chromium.org>
1 file changed